1. Technical Field
The present invention relates to an imaging optical element applicable to an image reading apparatus, such as an image scanner.
2. Related Art
In the related art, an image scanner that performs reading of text, images or the like recorded on a reading target is known as an image reading apparatus. Such an image scanner includes an imaging optical element including a lens array in which a plurality of lenses is arranged in a row form, and a light blocking member in which through holes are formed corresponding to the plurality of lenses in order that an optical image of the reading target may be formed by an image sensor including a plurality of imaging element arranged in a row form (for example, JP-A-2000-221442).
In such an imaging optical element, since the light blocking member allows light necessary in image formation to pass through the through holes whereas blocks light that is unnecessary in image formation, the optical image of the reading target is correctly formed in the image sensor.
Incidentally, in such an imaging optical element, light incident on the image sensor without being reflected by the inside surface of the through holes and light incident on the image sensor after being reflected by the inside surface of the through holes are included in the light that passes through the through holes in the light blocking member. The light reflected by the inside surface of the through holes becomes stray light by proceeding in a direction deviating from the optical axis of the lens, and is easily received at a position different from the primary image forming position on the image sensor. In this case, there is a problem if the imaged optical image becomes blurred by such stray light contributing to the image formation of the optical image on the image sensor.